Merge pull request #151 from basho/adt-disable-date-rotation
Can't disable periodic file rotation
diff --git a/README.md b/README.md
index 7c00447..116be24 100644
--- a/README.md
+++ b/README.md
@@ -81,7 +81,6 @@
{lager_console_backend, info},
{lager_file_backend, [{file, "error.log"}, {level, error}]},
{lager_file_backend, [{file, "console.log"}, {level, info}]}
- ]}
]}
]}.
```
@@ -102,7 +101,6 @@
{lager_file_backend, [{name, "error.log"}, {level, error}, {formatter, lager_default_formatter},
{formatter_config, [date, " ", time," [",severity,"] ",pid, " ", message, "\n"]}]},
{lager_file_backend, [{name, "console.log"}, {level, info}]}
- ]}
]}
]}.
```
@@ -154,11 +152,13 @@
asynchronous depending on mailbox size.
```erlang
-{async_threshold, 20}
+{async_threshold, 20},
+{async_threshold_window, 5}
```
This will use async messaging until the mailbox exceeds 20 messages, at which
-point synchronous messaging will be used.
+point synchronous messaging will be used, and switch back to asynchronous, when
+size reduces to `20 - 5 = 15`.
If you wish to disable this behaviour, simply set it to 'undefined'. It defaults
to a low number to prevent the mailbox growing rapidly beyond the limit and causing
diff --git a/src/lager.app.src b/src/lager.app.src
index 5c88a0b..63f35ce 100644
--- a/src/lager.app.src
+++ b/src/lager.app.src
@@ -53,6 +53,9 @@
%% How many messages per second to allow from error_logger before we start dropping them
{error_logger_hwm, 50},
%% How big the gen_event mailbox can get before it is switched into sync mode
- {async_threshold, 20}
+ {async_threshold, 20},
+ %% Switch back to async mode, when gen_event mailbox size decrease from `async_threshold'
+ %% to async_threshold - async_threshold_window
+ {async_threshold_window, 5}
]}
]}.
diff --git a/src/lager_app.erl b/src/lager_app.erl
index 148742f..d169f80 100644
--- a/src/lager_app.erl
+++ b/src/lager_app.erl
@@ -42,7 +42,20 @@
{ok, undefined} ->
undefined;
{ok, Threshold} when is_integer(Threshold), Threshold >= 0 ->
- _ = supervisor:start_child(lager_handler_watcher_sup, [lager_event, lager_backend_throttle, Threshold]),
+ DefWindow = erlang:trunc(Threshold * 0.2), % maybe 0?
+ ThresholdWindow =
+ case application:get_env(lager, async_threshold_window) of
+ undefined ->
+ DefWindow;
+ {ok, Window} when is_integer(Window), Window < Threshold, Window >= 0 ->
+ Window;
+ {ok, BadWindow} ->
+ error_logger:error_msg(
+ "Invalid value for 'async_threshold_window': ~p~n", [BadWindow]),
+ throw({error, bad_config})
+ end,
+ _ = supervisor:start_child(lager_handler_watcher_sup,
+ [lager_event, lager_backend_throttle, [Threshold, ThresholdWindow]]),
ok;
{ok, BadThreshold} ->
error_logger:error_msg("Invalid value for 'async_threshold': ~p~n", [BadThreshold]),
diff --git a/src/lager_backend_throttle.erl b/src/lager_backend_throttle.erl
index 34ff46e..14573b0 100644
--- a/src/lager_backend_throttle.erl
+++ b/src/lager_backend_throttle.erl
@@ -31,12 +31,13 @@
-record(state, {
hwm,
+ window_min,
async = true
}).
-init(Hwm) ->
+init([Hwm, Window]) ->
lager_config:set(async, true),
- {ok, #state{hwm=Hwm}}.
+ {ok, #state{hwm=Hwm, window_min=Hwm - Window}}.
handle_call(get_loglevel, State) ->
@@ -48,12 +49,12 @@
handle_event({log, _Message},State) ->
{message_queue_len, Len} = erlang:process_info(self(), message_queue_len),
- case {Len > State#state.hwm, State#state.async} of
- {true, true} ->
+ case {Len > State#state.hwm, Len < State#state.window_min, State#state.async} of
+ {true, _, true} ->
%% need to flip to sync mode
lager_config:set(async, false),
{ok, State#state{async=false}};
- {false, false} ->
+ {_, true, false} ->
%% need to flip to async mode
lager_config:set(async, true),
{ok, State#state{async=true}};
